The present invention includes methods and apparatus for making connections to an integrated circuit chip. The Tape-Automated Bonding Frame Adapter System provides a versatile and reliable device that provides increased lead density in a simplified and cost-effective package design.
Each year integrated circuits become more powerful and capable of storing more information. One of greatest challenges confronting designers in the electronics industry is finding more efficient and reliable methods to access the complex circuitry that resides within the chip package. A large rectangular IC chip having sides less than one half inch in length may have as many as five hundred or more leads extending from it. Each of these conductors must be physically bonded or coupled to external devices.
The basic methods of packaging integrated circuit chips utilize a technique called "tape-automated bonding." This fabrication procedure is commonly referred to by the acronym "TAB" and is well known to persons ordinarily skilled in the electronics packaging art. A continuous insulative tape which is similar to photographic film provides a basis for chips that are mounted on individual sections or frames of the tape. Sections or frames of TAB tape are generally rectangular or square sections that are arranged side-by-side along an uncut tape. A spider-like metal pattern of conductive traces is formed on each frame. The traces radiate from the center of the frame to its four edges. A chip is attached to the center of the TAB frame, so that the leads or contacts of the chip are mated with the corresponding metal traces in the central portion of the TAB frame. The resulting assembly comprising the chip, the TAB frame, and the substrate is essentially a space transformer that employs diverging radial electrical pathways to afford ready access to the integrated circuit.
Even this advanced TAB technology, however, is limited by the interface at the surface of the printed circuit board on which it resides. Conventional TAB devices require finely spaced or "pitched" patterns of metal pads on the printed circuit board. The problem of providing a high-density TAB assembly that is compatible with standard surface mount devices has presented a major challenge to designers in the automated electronic packaging field. The development of a rugged, precisely-aligned, and versatile system that does not suffer from the obstacles encountered during the manufacture of conventional TAB hardware would constitute a major technological advance in the electronics business. The enhanced performance that could be achieved using such an innovative device would satisfy a long felt need within the industry and would enable electronic equipment manufacturers to save substantial expenditures of time and money.